United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/SR-95/158 February 1996
4>EPA Project Summary
Identification of CFC and HCFC
Substitutes for Blowing
Polyurethane Foam Insulation
Products
Philip H. Howard, Jay L. Tunkel, and Sujit Banerjee
Substantial effort is ongoing to iden-
tify and evaluate third-generation blow-
ing agents for polyurethane foams to
replace currently used stratospheric
ozone depleting ones. Work under a
cooperative agreement between the
Environmental Protection Agency and
Syracuse Research Corporation has
identified and ranked over 100 chemi-
cals as polyurethane foam blowing
agent candidates. The systematic in-
vestigation involved the analysis of va-
por thermal conductivity predictive
models and utilizing this methodology
to identify and screen potential new
foam blowing agents. Collection of
physical/chemical properties of the new
candidates enabled an overall evalua-
tion. Based on the vapor thermal con-
ductivity, boiling point, and other
important properties, the chemical com-
pounds were ranked to identify the
most promising new blowing agent can-
didates. To efficiently evaluate new
foam blowing agents, the compounds
were placed and evaluated in 14 groups
based on chemical structure. Com-
pounds ranked high in this exercise
included cyclopentane and cyclo-
pentene, simple olefins consisting of
hydrocarbons with four to six carbons
and at least one double bond, cyclobu-
tane analogs, and fluorinated propanes
and butanes. Several novel chemical
groups, such as fluoroiodoalkanes and
silicon compounds, were also consid-
ered and ranked.
This Project Summary was developed
by EPA's National Risk Assessment
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Overview
Chlorofluorocarbons (CFCs) are recog-
nized as a major contributor to the deple-
tion of stratospheric ozone in the Earth's
atmosphere. Stratospheric ozone helps fil-
ter harmful ultraviolet (UV) radiation and
decreases the amount that reaches the
Earth's surface. Because of the potential
for harm to health and the environment as
a result of the increased incidence of UV
radiation, the phaseout of production of
CFCs was called for as of January 1,
1996, under the auspices of the Montreal
Protocol and current U.S. law.
CFCs were widely used as blowing
agents for rigid polyurethane foams for
insulation products due to their unique
combination of desirable physical/chemi-
cal properties and safety in use. World-
wide efforts to replace CFC blowing agents
led to the development of the so-called
second-generation blowing agents, the
hydrochlorofluorocarbons (HCFCs).
HCFCs have significantly lower ozone
depletion potentials compared to CFCs,
and many of these second-generation
blowing agents could be used directly as
drop-in replacements for CFCs. HCFCs,
however, also face phaseout under the
Montreal Protocol and subsequent agree-
ments due to their contribution to strato-
spheric ozone depletion; thus, they
represent only an interim replacement for
CFCs.
There is a need to identify chemical
compounds that are not stratospheric
ozone depleters that can be used as sub-
stitutes for CFC and HCFC blowing agents
in rigid polyurethane foam insulating ma-
terials. The search for these compounds
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is complicated by the facts that they must
possess unique physical/chemical proper-
ties and they must be compatible with
foam feedstocks and production methods.
Subtle differences between the third-gen-
eration blowing agents and CFCs or
HCFCs may result in modification of pro-
duction methods as well as differences in
use and utility of the foam product.
Substantial effort has been expended
by government, industrial, and private labo-
ratories to identify and evaluate third-gen-
eration blowing agents. A cooperative
agreement between the Environmental
Protection Agency and Syracuse Research
Corporation was designed to identify ad-
ditional polyurethane foam blowing agent
candidates in order to improve the chances
of finding successful ones. A systematic
search was conducted to identify new com-
pounds that could replace the CFCs and
HCFCs currently in use. The project in-
volved the analysis and use of vapor ther-
mal conductivity predictive models. The
vapor thermal conductivity of the blowing
agent is an important physical property for
insulating materials because the blowing
agent becomes incorporated into the foam
and, therefore, is partially responsible for
hindering the movement of heat through
the foam. Given that experimental vapor
thermal conductivity values are essentially
limited to currently available blowing agents
and refrigerants (which are mostly CFCs
and HCFCs) and that experimental mea-
surements of many compounds would be
economically prohibitive, a model to rap-
idly screen many compounds would be
advantageous in identifying new blowing
agents. Current models for estimating va-
por thermal conductivity were evaluated,
fine-tuned to reflect the current body of
knowledge in this area, and used to iden-
tify and screen potential new foam blow-
ing agents.
The study also included the identifica-
tion of potential new foam blowing chemi-
cals and their properties and the collection
of physical/chemical properties and other
data on the new candidates. Based on
the vapor thermal conductivity, boiling
point, and other important properties of
each candidate, over 100 chemical com-
pounds identified in this study were ranked
to identify the most promising new blow-
ing agent candidates. To efficiently evalu-
ate new foam blowing agents, the
compounds were placed in 14 groups
based on chemical structure. By placing
compounds in chemical groups, similari-
ties could be discussed collectively and
trends that represent differences could be
identified.
Compounds ranked high in this exer-
cise included cyclopentane and
cyclopentene, simple olefins consisting of
hydrocarbons with four to six carbons and
at least one double bond, cyclobutane ana-
logs, and fluorinated propanes and
butanes. For many other chemical groups,
a high potential was noted, but gaps in
available data prevented their ranking from
being higher. Several novel chemical
groups, such as fluoroiodoalkanes and sili-
con compounds, were also considered and
ranked.
Philip H. Howard and Jay L. Tunkel are with Syracuse Research Corp., Syracuse,
NY 13201; and Sujit Banerjee is with BRI, Atlanta, GA 30357.
Robert V. Hendriks is the EPA Project Officer (see below).
The complete report, entitled "Identification of CFC and HCFC Substitutes for
Blowing Polyurethane Foam Insulation Products," (Order No. PB96-113667;
Cost: $27.00, subject to change) will be available only from
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management
Research Laboratory (G-72)
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/SR-95/158
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